This invention relates to package inserts. More particularly, this invention relates to a laminated package insert produced by adhering two identical blanks face-to-face.
In packaging, and particularly in corrugated paperboard packaging, inserts are used in packages to divide the package into compartments and, more significantly, to provide vertical compressive strength or "stack strength". Originally, these inserts were single-walled pieces interlocked with slits in other pieces, such as in the familiar "egg crate" insert, or folded and glued into a desired shape, and placed in the package with their principal planes parallel to the direction of compression of the package. Additional compressive strength was obtained by using additional pieces in the insert. However, that had the effect of further reducing the available volume inside the package, as each piece occupied part of the package interior. It also resulted in smaller compartments in the package, restricting the types of articles that could be packed in a particular size of package. Compressive strength could also be increased by using heavier material, such as heavier paperboard, for the inserts. However, the heavier material is thicker and therefore also occupies additional volume.
Later, it was found that strength could be gained by forming inserts from multiple layers--e.g., two layers--by folding a layer of material on itself before folding it to form the insert. Once this was done, it was realized that by properly scoring, cutting and, if desired, selectively glueing, the folded-over insert, a single multiple layer insert in which the layers were adhered only in selected areas could be erected into a multiple compartment structure.
It is known to form such inserts from a single blank which is scored with a desired score pattern and then folded on itself to provide a two-layer structure which may then be selectively adhered, if desired. However, such blanks are typically scored using die-cutting techniques, in which only one side of the bank can be scored. Therefore, some scores in the blank are intended to be broken backwards, i.e., to be folded against their natural folding direction, resulting in frequent poor fold lines when such inserts are erected. In addition, it is more difficult for automatic insert erection equipment to erect an insert when it has to break score lines backwards. Although one such insert is known in which the scoring is done using slotter-scorer type apparatus, allowing the score lines to be formed from both sides of the blank, that insert was not glued together once folded because it was believed that such glueing would weaken the insert if the blank was not perfectly folded and aligned when glued. In addition, if an insert is formed from a folded blank, and then placed in the package such that the compressive forces are directed against the radius of the fold, the insert tends to buckle at the fold.
It would be desirable to be able to provide a multiple layer insert which can be erected easily by hand or by automatic insert erecting machinery and is stronger than previous multiple layer inserts for the same grade of board stock.
It would also be desirable to be able to provide a method and apparatus for forming the insert.